JPL: Orbital Ephemerides of the Sun, Moon, and Planets (DE405/LE405) (2003)
ftp://ssd.jpl.nasa.gov/pub/eph/planets/ioms/ExplSupplChap8.pdf
JPL: The Planetary and Lunar Ephemerides DE430 and DE431 (2014)
https://ipnpr.jpl.nasa.gov/progress_report/42-196/196C.pdf
Models for Propagation of NORAD...